CEO Vickie Kaminski says six patients in a unit at the hospital in St. John's have contracted C. difficile, three of whom have died.
She says doctors have since confirmed the patients did not die from C. difficile, but succumbed to illnesses they were already struggling with.
Samples have been sent to a lab in Winnipeg to determine whether or not the six patients had the same strain of the bacteria.
The results will help officials determine whether the bacteria was acquired inside or outside of the hospital.
Kaminski says the health authority is concerned the potential outbreak occurred around the same time a hand hygiene audit of staff showed less than favourable results.